; class Osteichthyes)
Often ranked as a subclass, the group that includes the extant lungfish and their fossil relatives. The lungfish are an order of bony fish (Osteichthyes) in the subclass Choanichthyes (Sarcopterygii), or fleshy-finned fish. They first appear in early Devonian rocks and were common in freshwater habitats in the late Palaeozoic and Triassic. Thereafter their fossil remains are very sparse and now there are just three surviving types, all in the tropics. See also Ceratodiformes.
Subjects: Zoology and Animal Sciences.